Ignition switches

ABSTRACT

An ignition switch comprises a casing and a rotor mounted in the casing for rotation within the casing from a stable first position to a stable second position and from the stable second position to an unstable third position, from which the rotor is resiliently urged back to said second position. First and second fixed contacts are supported in the casing and a first bridging member is rotatable with the rotor and operable to complete an electrical circuit between the first and second fixed contacts in the third position of the rotor. An arcuate cam track is provided on the inner surface of the casing and said first bridging member is resiliently urged into engagement with the cam track. The arrangement of the cam track is such that during movement of the rotor from the second position to the third position unless the preceding movement of the rotor was from the first position to the second position, the first bridging member is moved by the cam track in a direction such that in the third position the circuit between the first and second fixed contacts is not completed.

1 1 Mar. 27, 1973' [54] IGNITION SWITCHES [76] Inventor: Alec John Heap, 18 Brunshaw Avenue, Burnley, England 22 Filed: Nov. 18,1971

21 Appl.No.: 199,874

FOREIGN PATENTS OR APPLICATIONS 1,525,502 6/1967 France ..200/44 1,131,465 6/1962 Germany ..200/44 1,160,140 7/1969 Great Britain ..200/44 Primary Examiner-Robert K. Schaefer Assistant Examiner-William J. Smith Attorney-Holman & Stern [57] ABSTRACT An ignition switch comprises a casing and a rotor mounted in the casing for rotation within the casing from a stable first position to a stable second position and from the stable second position to an unstable third position, from which the rotor is resiliently urged back to said second position. First and second fixed contacts are supported in the casing and a first bridging member is rotatable with the rotor and operable to complete an electrical circuit between the first and second fixed contacts in the third position of the rotor. An arcuate cam track is provided on the inner surface of the casing and said first bridging member is resiliently urged into engagement with the cam track. The arrangement of the cam track is such that during movement of the rotor from the second position to the third position unless the preceding movement of the rotor was from the first position to the second position, the first bridging member is moved by the cam track in a direction such that in the third position the circuit between the first and second fixed contacts is not completed.

4 Claims, 5 Drawing Figures IGNITION SWITCHES This invention relates to ignition switches for road vehicles.

An ignition switch, according to the invention, comprises a casing, a rotor mounted in the casing for rotation within the casing from a stable first position to a stable second position and from the stable second position to an unstable third position from which the rotor is resiliently urged back to said second position, first and second fixed contacts supported in the casing, a first bridging member rotatable with the rotor and operable to complete an electrical circuit between said first and second fixed contacts in said third position of the rotor, and an arcuate cam track on the inner surface of the casing, said first bridging member being resiliently urged into engagement with said cam track, and the arrangement of said cam track being such that during movement of the rotor from said second position to said third position unless the preceding movement of the rotor was from the first position to the second position said first bridging member is moved by said cam track in a direction such that in said third position said circuit between the first and second fixed contacts is not completed.

Preferably, the switch further includes a third fixed contact and a second bridging member movable with the rotor, the second bridging member serving to bridge the first and third fixed contacts in the second and third positions of the rotor, and the first fixed contact defining the feed terminal of the switch.

Desirably, in the third position of the rotor the first bridging member is engaged with the second fixed contact and is engageable with said second bridging member so that when the first bridging member engages the second bridging member the circuit between the first and second fixed contacts is completed through the first and second bridging members.

Conveniently, when the rotor is moved to the third position from the second position without previously being moved from the first position to the second position the first bridging member is displaced by the cam track out of engagement with the second bridging member so that the circuit between the first and second fixed contacts is not completed. I

Alternatively, in the third position of the rotor the first bridging member is engaged with the second bridging member and is engageable with the second fixed contact so that when the first bridging member engages the second fixed contact the circuit between the first and second fixed contacts is completed through the first and second bridging members.

Conveniently, when the rotor is moved to the third position from the second position without previously being moved from the first position to the second position the first bridging member is displaced by the cam track in a direction away from the second fixed contact so that the circuit between the first and second fixed contacts is not completed in the third operative posi- In the accompanying drawings,

FIG. 1 is a sectional view of part of an ignition switch according to one example of the invention,

FIG. 2 is a plan view of the switch shown in FIG. 1 with the rotor removed for clarity,

FIG. 3 is an exploded, fragmentary perspective view of the casing of the switch shown in FIG. 1,

FIG. 4 is a sectional view of an ignition switch according to a second example of the invention, and

FIG. 5 is a sectional viewalong the line A-A in FIG. 4.

Referring to FIGS. 1 to 3 of the drawings, the switch includes a cylindrical casing 11 closed at one end thereof by a base 12. Housed within the casing 11 is a rotor 13, the rotor 13 being rotatable in the casing and including at its end remote from the base 12 an integral, axially extending spigot 14. The spigot 14 is provided with a non-circular bore 15 which in use receives a non-circular shaft (not shown) coupled to the rotatable core of a key operated cylinder lock, the rotor 13 t being driven in use by the core of the lock and the cylinder of the lock being defined by the switch casing 11.

Mounted on the rotor 13 for rotation therewith is a contact plate 16, the contact plate 16 including a pair of slots 17 on opposite sides respectively of the plate 16 and the rotor 13 being formed integrally with a pair of lugs 18 which located in the slots 17 respectively to mount the contact plate 16 for rotation with the rotor 13. Engaged between the contact plate 16 and the rotor 13 is a contact member 19, the contact member 19 being rotatable with the rotor and defining with the contact plate 16 the movable contacts of the switch. Mounted on the base 12 soas to extend into the casing 11 are a plurality of fixed contacts 21,22 (FIG. 2), 23 and 24, the contact plate 16 and the contact member 19 being resiliently urged by springs 25 towards the base 12 so as to complete electrical circuits between the fixed contacts during rotational movement of the rotor 13.

In use, the switch is intended for use as the ignition switch of a road vehicle, the fixed contact 21 being connected to one terminal of the vehicle battery to define the feed terminal of the switch and the fixed contacts 22,23 and 24 being connected in an accessories circuit, the ignition circuit and the starter motor circuit of the vehicle respectively. As can'be seen from FIG. 1, the feed contact 21 is positioned on the axis of rotation of the rotor 13 and hence is engaged by the contact plate 16 in all angular positions of the rotor. The rotor l3.is movable in one angular direction from an off position, in which no electrical circuits are made, to a stable, first operative position in which the contact plate 16 bridges the accessories circuit of the vehicle. From the first position, the rotor 13 is movable in said one angular direction to a stable, second operative position in which the contact plate 16 remains in engagement with the accessories contact 22 and also bridges the ignition contact 23 and the terminal 21 so as to complete the ignition circuit, as well as the accessories circuit of the vehicle. From said second position, the rotor 13 is movable in said one angular direction to an unstable, third operative position in which the contact member 19 engages the starter motor contact 24 whereby the starter motor circuit of the vehicle is normally completed by way of the feed terminal 21, the contact plate 16, the contact member 19 and the contact 24. The ignition circuit is also completed by the contact plate 16 in the operative third position of the switch. In the third position, the rotor 13 is resiliently urged towards the second operative position by a spring 26 which is mounted around the spigot l4 for rotational movement with the rotor 13, the spring 26 engaging a fixed stop on the casing 11 during movement of the rotor 13 from the second position to the third position so as to be flexed in said third operative position.

In addition to the fixed contacts of the switch, the base 12 is provided with an upstanding cylindrical portion 12a which is formed on its inside surface remote from the fixed contact 24 with an arcuate cam track 27. The cam track 27 extends intermediate the ends of a substantially flat, radially inwardly extending surface 28 and includes a raised plateau 29 defining at its summit a substantially flat, radially inwardly extending cam surface 31. The surface 28 extends further into the casing 11 than the cam surface 31 and so defines with the plateau 29 and arcuately extending shoulder 32. Intermediate its ends, the plateau 29 is stepped to define a wide portion 29a and a narrow portion 29b so that the shoulder 32 is formed as two arcuately extending, radially spaced parts 32a, 32b defined between the surface 28 and the portions 29a, 29b respectively. Further the height of the shoulder part 32a decreases towards its end adjacent the part 29b to define an inclined surface 33 extending between the surface 28 and the cam surface 31. Also the plateau 29 adjacent its end remote from the portion 32b tapers towards the base portion 12a so that the distance the cam surface 31 extends into the casing 11 decreases to a zero value at said one end of the plateau 29.

The arrangement of the switch is such that the contact member 19 is resiliently urged towards the surface 28 by the springs 25 and during angular movement of the rotor 13 a cam follower 34 formed at one end of the contact member 19 is engageable with the cam track 27. In order to allow the cam follower 34 to move over the cam track 27, the contact member 19 is capable of radial movement relative to the casing 11 and the base portion 12a, a helical compression spring 35 urging the cam follower portion 34 radially towards the cam track 27. The helical compression spring 35 is mounted in a recess 36 in the rotor 13 and acts between one end of the recess 36 and an upstanding finger 37 on the con-I tact member 19. Further, although one of the springs 25 extends through an aperture 38 in the contact member 19 to urge the contact plate 16 towards the base 12, the dimensions of the aperture 38 are such as to allow radial movement on the contact member 19 relative to the spring 25.

In operation, as the rotor 13 is moved from the off position of the switch towards the first operative position of the switch the cam follower 34 moves parallel to but is spaced above the surface 28. In the first operative position, as stated above, the accessories circuit of the vehicle incorporating the switch is made and during further movement of the rotor 13 from the first operative position towards the second operative position the cam follower 34, as it moves over the surface 28, engages the shoulder 32 at the tapered end of the plateau 29. Thus during further movement of the rotor 13 towards the second operative position, the portion 34 moves alongthe shoulder part 32aand so is urged by the part 32a radially into the casing 11 against the action of the spring 35.-The cam follower 34 remains in engagement with the part 32a in the second operative position of the switch, in which the ignition circuit of the vehicle is completed, but when the rotor 13 is 'cam surface 28 onto the inclined surface 33. Further movement of the rotor 13 under the resilient action of the spring 26 into the second operative position moves the cam follower 34 along the surface 33 and into engagement with ,the cam surface 31. The contact member 19 is then urged by the spring 35 in a direction to move the cam follower 34 radially outwardly towards the base portion 12a although a fixed stop (not shown) prevents the portion 34 from actually engaging the base portion 120. If the rotor is now immediately moved back into the third operative position, without initially going to the first operative position, then the cam follower portion 34 will be constrained to move over the region of the cam surface 31 defined above the narrow portion 290 of the plateau 29. The height of the cam surface 31 above the cam surface 28 is arranged to be such that, when the cam follower 34 is in engagement with the cam surface 31, the contact member 19 is pivoted about its end remote from the cam follower 34 so that the member 19 is spaced from the contact plate 16 wherebythe circuit between the terminal 21 and the contact 24 is not completed. Thus, if the rotor 13 is moved from the second operative position to the third operative position without initially being moved through the first operative position the starter motor circuit, which should be completed in the third operative position, is not completed.

However, if the rotor 13, after being resiliently urged from the third operative position to the second operative position, is moved towards the first operative position the portion 34 is moved along the cam surface 31 and over the tapered end of the plateau 29 to a position above the cam surface 28. Thus if the rotor 13 is now moved from the first operative position through the second position to the third operative position, the cam follower 34 is constrained to move over the cam surface 28 so that in the third operative position the contact member 19 remains in engagement with the contact plate 16 so that the starter motor circuit of the vehicle is completed.

ln a second example of the invention, as illustrated in FlGS. 4 and 5, the switch includes a cylindrical, twopart casing 41 in which is housed a rotor 42 so that the rotor 42 is rotatable in the casing. The rotor 42 carries at one end a metal plate 43 for rotation with the rotor and receives at its other end a non-circular shaft coupled to the rotatable core of a key operated cylinder lock, the rotor 42 being driven in use by the core of the lock and the cylinder of the lock being defined by the switch casing 41. The ignition switch of this second example of the invention also provides a lock for the gear box of the road vehicle using the switch, whereby movement of the gear selector shaft 44 of the road vehicle is prevented when the switch is in the locking position. The gear box lock feature of the switch is provided by a ball 45 engaged with the plate 43 and urged into a recess 46 in the shaft 44 when the switch is in the locking position by a cam surface (not shown) formed on the surface of the plate 43 remote from the rotor 42. Of course, it is to be appreciated that the switch according to the first example of the invention could have been provided with means for preventing movement to the gear selector shaft of the vehicle using the switch in a locking position of the switch.

Carried by the rotor 42 for rotation with the rotor are a contact plate 47 and a contact member 48, the contact member 48 being urged by a spring 49 into engagement with the contact plate 47. The contact plate 47 and the contact member 48 define the movable contacts of the switch and supported by the casing 41 are a plurality of angularly spaced fixed contacts 51,52,53 and 54. The spring 49 urges the contact member 48 and the contact plate 47 towards the fixed contacts so that the plate 47 and the member 48 complete electrical circuits between the fixed contacts during rotational movement of the rotor 42.

When the switch is in use on a road vehicle, the fixed contact 51 is connected to one terminal of the vehicle battery to define the feed terminal of the switch and the fixed contacts 52,53 and 54 are connected in an accessories circuit, the ignition circuit and the starter motor circuit of the vehicle respectively. The fixed contact 51 is positioned adjacent the axis of rotation of the rotor 42 and is arranged so that the contact plate 47 engages the fixed contact 51 in each of three operative positions of the rotor, but is spaced from the contact 51 in an inoperative position of the rotor. Thus, in the inoperative position no electrical circuits are made, the rotor then being movable in a clockwise direction as shown in FIG. 5 to a stable, first operative position in which the contact plate 47 bridges the accessories contact 52 and the feed terminal 51 so as to complete the accessories circuit of the vehicle. From the first operative position, the rotor 42 is movable in a clockwise direction to a stable, second operative position in which the contact plate 47 engages the feed terminal 51, the accessories contact 52 and the ignition contact 53 so as to complete both the ignition circuit and the accessories circuit of the vehicle. From the second operative position, the rotor 42 is movable in a clockwise direction to an unstable, third operative position in which the contact plate bridges the ignition contact 53 and the feed terminal 51 to complete the ignition circuit and the contact member 48 normally engages the starter motor contact 54 whereby the starter motor circuit is normally completed by way of the contact 54, the member 48, the plate 47 and the feed terminal 51. A spring 55 is flexed during movement of the rotor from the second operative position to the third operative position so that the rotor 42 is resiliently urged from the third operative position towards the second operative position. The rotor 42 also carries a spring urged ball 56 which engages and moves over a detent surface 57 during rotational movement of the rotor 42, whereby-the rotor is releasably retained in the inoperative position and each of the first and second operative positions.

The casing 11 of the switch is formed on its inside surface with an arcuate cam track 58 and the contact member 48 is formed with a cam follower 59 which is resiliently urged into engagement with the cam track 58 by the spring 49 and a further spring 61, the contact member 48 being movable radially in the casing 11 against the resilient action of the spring 61. The cam track 58 is substantially the same as the cam track 47 described in the first example of the invention and shown in FIG. 3, the arrangement of the switch according to the second example being such that if the rotor 42 is moved from the second operative position to the third operative position without previously being moved from the first operative position to the second operative position the contact member 48 is moved in a direction away from the fixed contact 54, whereby in the third operative position the contact member 48 is spaced from the fixed contact 54 and the starter motor circuit of the vehicle is not completed. Of course, as in the previous example, if the rotor 42 is moved from the first operative position through the second position to the third operative position the contact member 48 engages the fixed contact 54 in the third operative position and the starter motor circuit of the vehicle is completed.

From the foregoing description, it will be appreciated that the arrangement of each of the switches described in the above examples is such that when in use on a road vehicle and the engine of the vehicle is running the starter motor circuit cannot be completed until the ignition circuit has been broken. Thus, when the switch is in use in a road vehicle, the driver of the vehicle cannot energize the starter motor of the vehicle when the engine is running, although the driver can still move the rotor 13 into the start position when the engine is running.

I claim:

1. An ignition switch comprising a casing, a rotor in the casing, means mounting the rotor for rotation within the casing from a stable first position to a stable second position and from the stable second position to an unstable third position from which the rotor is resiliently urged back to said second position, first and second fixed contacts supported in the casing, a first bridging member rotatable with the rotor and operable to complete an electrical circuit between said first and second fixed contacts in said first position of the rotor, an arcuate cam track on the inner surface of the casing, resilient means urging said first bridging member into engagement with said cam track, and a cam surface forming part of said cam track and being engageable by said first bridging member during movement of the rotor from said second position to said first position unless the preceding movement of the rotor was from the first position to the second position, said cam surface being arranged so as to move said first bridging member, when engaged by the bridging member, in a direction such that in said third position said circuit between the first and second fixed contacts is not completed.

2. A switch as claimed in claim 1 and further including a third fixed contact and a second bridging member movable with the rotor, the second bridging member serving to bridge the first and third fixed contacts in the second and third positions of the rotor, and the first fixed contact defining the feed terminal of the switch.

3. A switch as claimed in claim 1 wherein detent means releasably retains the rotor in each of said first and second stable positions.

4. A switch as claimed in claim 1 wherein the rotor is movable to a further stable position in which locking means operable by the rotor can prevent movement of the gear selector shaft of a vehicle using the switch. 

1. An ignition switch comprising a casing, a rotor in the casing, means mounting the rotor for rotation within the casing from a stable first position to a stable second position and from the stable second position to an unstable third position from which the rotor is resiliently urged back to said second position, first and second fixed contacts supported in the casing, a first bridging member rotatable with the rotor and operable to complete an electrical circuit between said first and second fixed contacts in said first position of the rotor, an arcuate cam track on the inner surface of the casing, resilient means urging said first bridging member into engagement with said cam track, and a cam surface forming part of said cam track and being engageable by said first bridging member during movement of the rotor from said second position to said first position unless the preceding movement of the rotor was from the first position to the second position, said cam surface being arranged so as to move said first bridging member, when engaged by the bridging member, in a direction such that in said third position said circuit between the first and second fixed contacts is not completed.
 2. A switch as claimed in claim 1 and further including a third fixed contact and a second bridging member movable with the rotor, the second bridging member serving to bridge the first and third fixed contacts in the second and third positions of the rotor, and the first fixed contact defining the feed terminal of the switch.
 3. A switch as claimed in claim 1 wherein detent means releasably retains the rotor in each of said first and second stable positions.
 4. A switch as claimed in claim 1 wherein the rotor is movable to a further stable position in which locking means operable by the rotor can prevent movement of the gear selector shaft of a vehicle using the switch. 